Current developments in wind turbine design often focus on large scale kilowatt and megawatt installations. In such cases, fewer, very-large blades have been found to be most efficient. For example, adding more than 3 blades to very large turbines has been reported to produce diminishing returns in energy production. Additionally, more blades on very large scale turbines results in a much noisier turbine due in part to the aerodynamic effects of air flowing over the blade surfaces. Moreover, large commercial turbine power generating systems need to be located in specific high-wind locations, such as the crests of hills in windy geographies.
Smaller scale applications, such as those related to domestic, marine, and remote field power generation, have different requirements. For example, domestic or mobile turbines, by their nature, may be placed in locations with inconsistent or low winds.
Current turbines of any size produce undesirable levels of noise, at least in part because of aerodynamic effects of current blade designs chopping the air (a constant whooshing sound). Accordingly, in some instances, users may lock such turbines and avoid their use when people are nearby, such as when a boat is occupied or when people nearby are sleeping. If a user chooses to lock a turbine at night to reduce noise, the undesirable noise has the ultimate effect of reducing the turbine's efficacy. Such undesirable noise levels may also contribute to the relatively higher popularity of solar energy for domestic, home-based, and/or off-grid power generation, despite the fact that solar power does not work at night, while wind power does. And current turbines are less portable than solar panels or batteries, so solar power and batteries are a predominant power source for remote uses by hikers or others in remote areas.
Accordingly, there is a need for quieter turbines, turbines that can generate power at low wind speeds, turbines with improved efficiency, and—for many applications—turbines and related assemblies for power generation that are light weight, resilient, and/or portable.
Such small-scale and/or local turbines can be referred to as distributed wind energy. Distributed wind energy is local wind energy production implemented near the site of energy use, as opposed to large-scale wind energy production like the wind farms operated by utility companies. Examples of distributed wind may include the above domestic, marine, and/or remote implementations. Distributed wind can be implemented to support off-grid sites or it can supplement on-grid sites.
The United States Department of Energy has recognized that distributed wind energy is not only feasible; it has the potential to become a major source of energy during the next several decades. But to become such a major source of energy, distributed wind devices need to be lower in cost, more efficient, and easier for consumers to implement.
Many shapes in nature have evolved over millions of years to provide efficient solutions to survival problems for natural organisms. Biomimicry in some manmade devices has taken advantage of concepts learned from analysis of natural biological solutions. One important mechanism is the fin of a humpback whale, which has structures called tubercles that scientists have credited with improved maneuverability and efficiency for the whale due to improved fluid dynamics.